It is well known that tobacco smoke contains a number of components which can have a harmful effect on smokers, especially when tobacco is smoked in the form of cigarettes.
One potentially harmful component of tobacco smoke is tar, but the tar content of cigarette smoke can be substantially reduced by using a tobacco which has a low tar content. In addition, it is well known to use filters which can either be integral with the cigarettes or which are present in a cigarette holder.
However, there are a number of potentially harmful components in cigarette smoke which are not removed by filters. These include not only hydrocyanic acid but also saturated and unsaturated aliphatic aldehydes, including acrolein, formaldehyde and acetaldehyde. Various health hazards have been ascribed to individual aldehydes: formaldehyde induces nasal cancers in rats, acetaldehyde has toxic effects on the myocardium and acrolein may induce bladder cancer and contribute to broncho-irritancy.
It is also known that certain anti-tumour agents are metabolised by the body to give metabolites which can themselves give rise to toxic lesions, many of which are highly organospecific. This highly undesirable side effect considerably restricts the therapeutic use and benefit of anti-tumour agents. Thus, by way of example, the well-known antineoplastic drug cyclophosphamide can give rise to haemorrhagic cystitis, this being due to the fact that cyclophosphamide is metabolised to give acrolein which is subsequently eliminated through the urinary system but which can give rise to neoplastic processes in the bladder.
Recent investigations have demonstrated that this highly undesirable effect of cyclophosphamide can be considerably or totally eliminated by the concurrent intravenous administation of .omega.-mercapto-alkane-sulphonates, preferably in the form of their non-toxic salts, such as the sodium salts thereof. Some of these compounds are known to be useful as mucolytic agents (see British Patent Specification No. 1 119 721).
Much effort has been devoted over the years to remove substances, such as acrolein and formaldehyde, from tobacco smoke but, despite these efforts, aldehyde reduction has not been achieved without concomitant unacceptable change in the taste characteristics.
We have now found that non-toxic salts of certain .omega.-mercapto-alkane-sulphonates, as well as cysteine and acetylcysteine, effectively lower the aldehyde and hydrocyanic acid content of tobacco smoke.